Movable barrier controllers are known in the art. Such devices typically respond to an actuation signal by actuating a motor and causing a movable barrier to move (the movable barrier can be, for example, a garage door, a date, a shutter, and the like). These devices have become increasingly sophisticated. For example, such controllers are often able to sense resistance to barrier movement. Such information can be used in a variety of ways, including automatically reversing movement of the barrier upon detecting an obstacle in the moving barrier's path. Unfortunately, a universal setpoint does not exist that will work for all barrier controllers systems to facilitate, under all operating conditions, utterly reliable obstacle detection with zero false positives all the time. Consequently, many barrier controllers include a force control that can be adjusted for an individual controller in a particular setting to better ensure safe, reliable, and effective operation.
Over the course of time, operating conditions for a given barrier controller can change. The barrier itself can be modified or exchanged for a different barrier. The barrier movement track can be altered (to obtain hoped-for improvement and/or through accident and mishap). The drive mechanism can also undergo change over time. For example, the motor and/or associated gear ratio can be changed (this often occurs in the context of maintenance and repair). Such changes can significantly impact the efficacy of previous force control settings. For example, consider FIG. 1. Torque/speed curves are depicted for three motors A, B, and C. For a given speed S, motor A has a corresponding torque T1, motor B has a corresponding torque T2, and motor C has a corresponding torque T3. These torques can differ considerably from one another and should ordinarily be taken into account when selecting a force control settings that correspond to a particular speed.
Unfortunately, the force control typically comprises a mechanical device having a corresponding mechanical setting range. As depicted in FIG. 2, a typical force control comprises a potentiometer having a user manipulative setting range that is bounded by a lower limit the and an upper limit. Ideally, this setting range should correspond to a useful setting range for a particular barrier controller system. Such correspondence allows for greater useful resolution and granularity of control. For a given set of conditions (including a known motor and gear ratio) such a setting range is achievable. As noted above, however, operating conditions often change over the useful life of a given barrier controller system. By changing motors, as noted above, torque at a given speed can change considerably. This change can make an existing user manipulative setting range of force control values as established for a first set of conditions quite inappropriate for a later set of conditions. For example, with reference to FIG. 3, a prior art force control as designed to accommodate a variety of operating circumstances (including different motors and gear ratios) may have a relatively small useful range of settings for a first motor (as depicted by range 1) and a similar relatively small useful range of settings for a second motor (as depicted by range 2).
A need therefore exists for a way to better accommodate subsequent operating system changes while providing an acceptable range of sensitivity control. Preferably, this need should be met in an economical and ergonomically sensitive manner. Further, minimized user responsibility to ensure such accommodation would be beneficial. Any such solution should also be relatively flexible and able to accommodate a relatively broad range of altered circumstances.